I would be very careful when enabling suppressed alarms (and I usually advise against it). When there are outages to core devices, this could cause thousands of suppressed alarms to generate. Suppressed alarms generate on application models and interfaces. So if you have a large network device with 500 interfaces go down, you are going to get at least 500 suppressed alarms (then all of the suppressed alarms for everything "downstream").
Instead, maybe a better option for you is to just delete the connections to the Voice models in the Topology view. If there is no connection, when the upstream device goes down, instead of suppressing the alarm, Spectrum will generate a Critical alarm on it (assuming you have the attribute set for value_when_red=7).
Cheers!
Jay